Can a Breakaway Battery and Deep Cycle Battery be Charged off of the Same 12 Volt Line

Published 11/07/2016

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Question:

I am planning to use the black 12V accessory wire from the harness to maintain my breakaway battery using a abcd charger and then using the same 12V source to maintain my deep cell battery for my trailer lights and invertor. Will the two batteries drain each other seeing how they are on the same 12V black accessory wire? Would another abcd type charger help maintain the deep cell battery better than just the black wire connected to it? What do I need?

asked by: Randy B

Expert Reply:

What you could do is use the center pin on a 7-Way and instead of having the reverse light circuit on that pin you could remove the wire that is there and run a 10 gauge wire, such as # 10-1-1 sold by the foot, from it up to the truck battery via a 40 amp circuit breaker # PK54540. Then run wire from the center pin on the trailer side to the deep cycle battery to maintain it. This way the batteries each have their own 12 volt source and there is no chance of back feeding.

Another option if you have to use the same 12 volt source is to put diodes, such as # RM-690, in line on the wiring going to each of the batteries. The diodes will only allow power to flow to the batteries and not from the batteries back to the 7-Way or each other.

If you want to actually charge up the deep cycle battery and not just keep it from draining then you will need to use a special DC to DC charger, # 331-BCDC1240D. The small breakaway battery chargers are designed for low amp hour breakaway batteries and would not be effective for a larger battery.

expert reply by: Michael H